Optical films for reducing color shift and organic light-emitting display apparatuses employing the same

ABSTRACT

Optical films, and organic-light-emitting display apparatuses, include a high refractive index pattern layer including a first surface and a second surface facing each other. The first surface includes a pattern having grooves. The grooves each have a curved surface and a depth greater than a width. The high refractive index pattern layer is formed of a material having a refractive index greater than 1. Further included is a low refractive index pattern layer formed of a material having a refractive index smaller than that of the material constituting the high refractive index pattern layer. The low refractive index pattern layer includes a filling material for filling grooves. A tilt angle, θ, of each groove satisfies the following condition, 15°≦θ≦75°.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority under 35 U.S.C. §119from Korean Patent Application No. 10-2013-0063113, filed on May 31,2013, in the Korean Intellectual Property Office, the disclosure ofwhich is incorporated herein by reference in its entirety.

BACKGROUND

1. Field

The present disclosure relates to optical films for reducing color shiftand/or organic light-emitting display apparatuses employing the same.

2. Description of the Related Art

An organic light-emitting diode (OLED) includes an anode, an organiclight-emitting layer, and a cathode. Here, when a voltage is appliedbetween the anode and the cathode, holes are injected from the anodeinto the organic light-emitting layer, whereas electrons are injectedfrom the cathode into the organic light-emitting layer. At this point,the holes and electrons injected into the organic light-emitting layerare re-combined and generate excitons, and light is emitted as theexcitons transit from excited state to ground state.

Because a light-emitting body of such an OLED is an organic material,the lifespan deterioration is the core problem regarding the developmentof OLED, and many techniques are being focused to resolve the problem.

From among the techniques, a technique using a microcavity structure isa technique for increasing an intensity of a light of a particularwavelength by resonating the light and emitting the light of theparticular wavelength to outside. In other words, the microcavitystructure is a structure in which distances between anodes and cathodesare designed to respectively correspond to representative wavelengths ofred (R), green (G), and blue (B), so that only light of wavelengthscorresponding thereto resonate and are emitted, and lights of otherwavelengths are weakened. As a result, light emitted to outside of thestructure becomes more intense and sharper, thereby improving brightnessand color purity. Furthermore, increased brightness causes reduced powerconsumption, thereby inducing increased lifespan.

However, in a microcavity structure, wavelengths to be amplified aredetermined based on a thickness of an organic deposition material layer.Here, a length of a light path changes at lateral sides, thereby causingan effect similar to a change in the thickness of an organic depositionmaterial layer. Therefore, the wavelengths to be amplified are changed.

In other words, as the viewing angle is tilted from the front to a side,the maximum resolution wavelength becomes shorter, and thus a colorshift occurs as the maximum resolution wavelength decreases. Forexample, even if white color is embodied at the front, the white colormay become bluish at a lateral side due to blue shift phenomenon.

SUMMARY

Provided are optical films for reducing color shift and/or organiclight-emitting display apparatuses employing the same.

According to some example embodiments, an optical film includes a highrefractive index pattern layer including a first surface and a secondsurface facing each other, wherein the first surface includes a patternhaving a plurality of grooves, the plurality of grooves each have ahcurved surface, and a depth greater than a width thereof, and the highrefractive index pattern layer is formed of a material having arefractive index greater than 1; and a low refractive index patternlayer formed of a material having a refractive index smaller than therefractive index of the material constituting the high refractive indexpattern layer, wherein the low refractive index pattern layer includes afilling material for filling the plurality of grooves, wherein the tiltangle is an angle between a straight line and the first surface, and thestraight line connects an apex of the respective groove to a start pointof an adjacent groove on the first surface.

The pattern having a plurality of grooves may be an engraved pattern.

The plurality of grooves may be collectively repeated in a cycle, C, andthe condition, A/C<0.5, may be satisfied where A is the width of thegroove.

The filling material may include air or a resin material.

The filling material may include a transparent plastic materialincluding a light diffuser or a light absorber.

The low refractive index pattern layer may be a film having a pluralityof protrusion patterns, and the plurality of protrusions may correspondto the plurality of grooves.

The low refractive index pattern layer may include a transparent plasticmaterial including a light diffuser or a light absorber.

The plurality of grooves may each have an extended stripe shape.

The plurality of grooves may each have a dot shape from a perspectiveview with respect to the high refractive index pattern layer.

The curved surface of the plurality of grooves may be an asphericalsurface.

The optical film may further include an anti-reflection layer on thehigh refractive index pattern layer; and a first adhesive layer underthe low refractive index pattern layer.

The optical film may further include a first base layer between the highrefractive index pattern layer and the anti-reflection layer.

The optical film may further include a circular polarization layerincluding a phase shift layer and a linear polarization layer.

The first adhesive layer, the low refractive index pattern layer, thehigh refractive index pattern layer, the phase shift layer, the linearpolarization layer, the first base layer, and the anti-reflection layermay be sequentially arranged.

The optical film may further include a second base layer and a secondadhesive layer, wherein the high refractive index pattern layer, thesecond base layer, the second adhesive layer and the phase shift layerare sequentially arranged.

The first adhesive layer, the phase shift layer, the linear polarizationlayer, the low refractive index pattern layer, the high refractive indexpattern layer, the first base layer, and the anti-reflection layer maybe sequentially arranged.

The optical film may further include a second base layer and a secondadhesive layer, wherein the linear polarization layer, the second baselayer, the second adhesive layer and the low refractive index patternlayer are sequentially arranged.

The first adhesive layer, the phase shift layer, the low refractiveindex pattern layer, the high refractive index pattern layer, the linearpolarization layer, the first base layer, and the anti-reflection layermay be sequentially arranged.

The optical film may further include a second base between the highrefractive index pattern layer and the linear polarization layer. Theoptical film may further include a phase shift layer, a linearpolarization layer, and a first base layer, wherein the first adhesivelayer, the phase shift layer, the linear polarization layer, the firstbase layer and the low refractive index pattern layer are sequentiallyarranged.

The optical film may further include a transmittance adjusting layerbetween the high refractive index pattern layer and the anti-reflectionlayer.

The optical film may further include a first carrier film between thehigh refractive index pattern layer and the transmittance adjustinglayer.

The optical film may further include a second adhesive layer between thefirst carrier film and the transmittance adjusting layer; and a secondcarrier film between the transmittance adjusting layer and theanti-reflection layer.

The optical film may further include a first carrier film between thetransmittance adjusting layer and the anti-reflection layer.

The optical film may further include a second adhesive layer between thehigh refractive index pattern layer and the transmittance adjustinglayer; and a second carrier film between the first adhesive layer andthe low refractive index pattern layer.

According to other example embodiments, an organic light-emittingdisplay apparatus includes an organic light-emitting display panelincluding a plurality of pixels emitting light of different wavelengthsand a plurality of organic light-emitting layers each having amicrocavity structure configured to resonate and emit light of acorresponding wavelength; and the optical film on the organiclight-emitting display panel.

The plurality of grooves may each have an extended stripe shape.

An extending direction of the plurality of grooves may correspond to avertical direction of the organic light-emitting display panel.

The plurality of pixels may be two-dimensionally arranged along avertical direction and a horizontal direction of the organiclight-emitting display panel, and the extending direction of the groovesand the vertical direction in which the plurality of pixels are arrangedmay be non-parallel to each other.

The organic light-emitting display device may further include a firstadhesive layer between the organic light-emitting display panel and thelow refractive index pattern layer; and an anti-reflection layer on thehigh refractive index pattern layer.

A first base layer may be between the high refractive index patternlayer and the anti-reflection layer.

The organic light-emitting display device may further include a circularpolarization layer including a phase shift layer and a linearpolarization layer.

The first adhesive layer, the low refractive index pattern layer, thehigh refractive index pattern layer, the phase shift layer, the linearpolarization layer, the first base layer, and the anti-reflection layermay be sequentially arranged.

The organic light-emitting display device may further include a secondbase layer and a second adhesive layer, wherein the high refractiveindex pattern layer, the second base layer, the second adhesive layerand the phase shift layer are sequentially arranged.

The organic light-emitting display device may further include atransmittance adjusting layer between the high refractive index patternlayer and the anti-reflection layer.

According to further example embodiments, an optical film includes arefractive layer formed of a refractive material having a refractiveindex greater than 1 and a medium having a refractive index smaller thanthe refractive index of the refractive material. An interface betweenthe refractive material and the medium has a pattern with a plurality ofrecesses. The plurality of recesses each have a curved surface and adepth greater than a width thereof. The medium fills the plurality ofrecesses. A tilt angle, θ, of each of the recesses is between 15°≦θ≦75°.The tilt angle is an angle between a straight line and the interface,and the straight line connects an apex of each recess to a neareststarting point, along the interface, of an adjacent recess.

The medium may be a gas or a solid.

The tilt angle, θ, of each of the recesses may be between 15°≦θ≦65°.

BRIEF DESCRIPTION OF THE DRAWINGS

Example embodiments will be more clearly understood from the followingdetailed description taken in conjunction with the accompanyingdrawings. FIGS. 1-26 represent non-limiting, example embodiments asdescribed herein.

FIG. 1 is an exploded perspective view of an optical film according tosome example embodiments;

FIG. 2 is a sectional view taken along a line A-A′ of FIG. 1, showing alight path in which light that is perpendicularly incident to theoptical film is emitted;

FIG. 3 is a sectional view taken along a line A-A′ of FIG. 1, showing alight path in which light that is incident to the optical film at atilted angle is emitted;

FIG. 4 is a computer simulation graph showing color shift according to avariation of tilt angle θ in the optical film of FIG. 1;

FIG. 5 is a computer simulation graph showing transmittance and colorshift according to a variation of pattern density in the optical film ofFIG. 1;

FIG. 6 is a schematic exploded perspective view of an optical filmaccording to other example embodiments;

FIG. 7 is a schematic exploded perspective view of an optical filmaccording to still other example embodiments;

FIG. 8 is a schematic exploded perspective view of an optical filmaccording to further example embodiments;

FIG. 9 is a schematic sectional view of an optical film according tostill further example embodiments;

FIG. 10 is a schematic exploded perspective view of an optical filmaccording to yet other example embodiments;

FIGS. 11 through 17 are schematic sectional views of optical filmsaccording to example embodiments employing circular polarization layersand anti-reflection layers;

FIGS. 18 through 21 are schematic sectional views of optical filmsaccording to example embodiments employing transmittance adjustinglayers and anti-reflection layers;

FIG. 22 is a sectional view of an organic light-emitting displayapparatus according to some example embodiments;

FIG. 23 schematically shows a relationship between arrangement of anadhesive layer and pixel arrangement of an organic light-emittingdisplay panel in the organic light-emitting display apparatus of FIG.22;

FIG. 24 is a graph showing a comparison between color shifts accordingto viewing angles in a case where an optical film according to exampleembodiments is employed and color shifts according to viewing angles ina conventional optical film;

FIG. 25 is a graph showing a comparison between brightnesses accordingto viewing angles in a case where an optical film according to exampleembodiments is employed and brightnesses according to viewing angles ina conventional optical film; and

FIG. 26 is a schematic sectional view showing an organic light-emittingdisplay apparatus according to other example embodiments.

DETAILED DESCRIPTION

Various example embodiments will now be described more fully withreference to the accompanying drawings in which some example embodimentsare shown. However, specific structural and functional details disclosedherein are merely representative for purposes of describing exampleembodiments. Thus, the invention may be embodied in many alternate formsand should not be construed as limited to only example embodiments setforth herein. Therefore, it should be understood that there is no intentto limit example embodiments to the particular forms disclosed, but onthe contrary, example embodiments are to cover all modifications,equivalents, and alternatives falling within the scope.

In the drawings, the thicknesses of layers and regions may beexaggerated for clarity, and like numbers refer to like elementsthroughout the description of the figures.

Although the terms first, second, etc. may be used herein to describevarious elements, these elements should not be limited by these terms.These terms are only used to distinguish one element from another. Forexample, a first element could be termed a second element, and,similarly, a second element could be termed a first element, withoutdeparting from the scope of example embodiments. As used herein, theterm “and/or” includes any and all combinations of one or more of theassociated listed items.

It will be understood that, if an element is referred to as being“connected” or “coupled” to another element, it can be directlyconnected, or coupled, to the other element or intervening elements maybe present. In contrast, if an element is referred to as being “directlyconnected” or “directly coupled” to another element, there are nointervening elements present. Other words used to describe therelationship between elements should be interpreted in a like fashion(e.g., “between” versus “directly between,” “adjacent” versus “directlyadjacent,” etc.).

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of exampleembodiments. As used herein, the singular forms “a,” “an” and “the” areintended to include the plural forms as well, unless the context clearlyindicates otherwise. It will be further understood that the terms“comprises,” “comprising,” “includes” and/or “including,” if usedherein, specify the presence of stated features, integers, steps,operations, elements and/or components, but do not preclude the presenceor addition of one or more other features, integers, steps, operations,elements, components and/or groups thereof.

Spatially relative terms (e.g., “beneath,” “below,” “lower,” “above,”“upper” and the like) may be used herein for ease of description todescribe one element or a relationship between a feature and anotherelement or feature as illustrated in the figures. It will be understoodthat the spatially relative terms are intended to encompass differentorientations of the device in use or operation in addition to theorientation depicted in the figures. For example, if the device in thefigures is turned over, elements described as “below” or “beneath” otherelements or features would then be oriented “above” the other elementsor features. Thus, for example, the term “below” can encompass both anorientation that is above, as well as, below. The device may beotherwise oriented (rotated 90 degrees or viewed or referenced at otherorientations) and the spatially relative descriptors used herein shouldbe interpreted accordingly.

Example embodiments are described herein with reference tocross-sectional illustrations that are schematic illustrations ofidealized embodiments (and intermediate structures). As such, variationsfrom the shapes of the illustrations as a result, for example, ofmanufacturing techniques and/or tolerances, may be expected. Thus,example embodiments should not be construed as limited to the particularshapes of regions illustrated herein but may include deviations inshapes that result, for example, from manufacturing. For example, animplanted region illustrated as a rectangle may have rounded or curvedfeatures and/or a gradient (e.g., of implant concentration) at its edgesrather than an abrupt change from an implanted region to a non-implantedregion. Likewise, a buried region formed by implantation may result insome implantation in the region between the buried region and thesurface through which the implantation may take place. Thus, the regionsillustrated in the figures are schematic in nature and their shapes donot necessarily illustrate the actual shape of a region of a device anddo not limit the scope.

It should also be noted that in some alternative implementations, thefunctions/acts noted may occur out of the order noted in the figures.For example, two figures shown in succession may in fact be executedsubstantially concurrently or may sometimes be executed in the reverseorder, depending upon the functionality/acts involved.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which example embodiments belong. Itwill be further understood that terms, such as those defined in commonlyused dictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the relevant art andwill not be interpreted in an idealized or overly formal sense unlessexpressly so defined herein.

In order to more specifically describe example embodiments, variousfeatures will be described in detail with reference to the attacheddrawings. However, example embodiments described are not limitedthereto.

FIG. 1 is an exploded perspective view of an optical film according someexample embodiments.

Referring to FIG. 1, an optical film 100 includes a high refractiveindex pattern layer 110 including a plurality of grooves GR havingcurved surfaces and a low refractive index pattern layer 120 which isformed on the high refractive index pattern layer 110. The lowrefractive index pattern layer 120 is formed of a material having alower refractive index than the material constituting the highrefractive index pattern layer 110, and includes a filling material forfilling the plurality of grooves GR.

The high refractive index pattern layer 110 may be formed of a materialhaving a refractive index greater than 1 (e.g., a transparent plasticmaterial). Furthermore, the optical film 100 may also be formed of atransparent plastic material including a light diffuser or a lightabsorbent. The light diffuser may be diffusing beads, and the lightabsorber may be a black dye, such as carbon black. The light diffuserimproves visibility property by flattening peaks that may be induced atcolor shifts based on angles and brightness profiles by particulargrooves. Meanwhile, the light absorber may contribute to improvedcontrast or color purity by using a dye for selectively absorbing lightof a particular wavelength or carbon black for absorbing light ofoverall visible ray wavelengths.

The groove GR is formed to have an aspect ratio greater than 1. In otherwords, the groove GR is formed to have a depth d greater than a width w,where the aspect ratio d/w may be greater than 1 and smaller than 3 andthe grooves GR may be repeatedly arranged at a set (or, predetermined)cycle C.

In the shape of the grooves GR shown in FIG. 1, a tilt angle θ of theapex of a groove GR with respect to a starting point of an adjacentgroove GR may be defined. The tilt angle θ is an angle formed between astraight line, which connects the apex of a groove GR and a startingpoint of an adjacent groove GR at a top surface of the high refractivepattern layer 110, and the top surface.

The tilt angle θ may be expressed as shown below in Equation 1 by usingdepth d, width A, and cycle C of the grooves GR.θ=tan⁻¹(d/(C−A/2))  Equation 1

The tilt angle θ defined as shown above may significantly affectperformance of the optical film 100, and more particularly, performancefor reducing color shift according to an increase in the viewing angle,and may satisfy the condition shown below in Equation 2.A/C<0.5  Equation 2

A surface forming the groove GR is a curved surface and may be anaspheric surface. For example, the curved surface constituting thegroove GR may be an elliptical surface, a parabolic surface, or ahyperbolic surface. Furthermore, the grooves G may extend like stripes.

A sum of widths of the plurality of grooves GR may occupy from about 25%to about 50% of a width of the high refractive index pattern layer 110.

As shown in FIG. 1, the low refractive index pattern layer 120 may beformed as a film having protrusions P corresponding to the plurality ofgrooves GR. In other words, the low refractive index pattern layer 120has a form which not only fills the plurality of grooves GR, but alsoincludes a flat portion with a set (or, predetermined) thickness.According to materials and methods for filling the grooves GR, athickness and a flatness of flat portions of the low refractive indexpattern layer 120 may vary. Furthermore, the low refractive indexpattern layer 120 may be formed of a material having a lower refractiveindex than the material constituting the high refractive index patternlayer 110. In other words, the low refractive index pattern layer 120may be formed of a transparent plastic material or a transparent plasticmaterial containing a light diffuser or a light absorber. The lightdiffuser may be diffusing beads, whereas the light absorber may be ablack dye, such as carbon black.

The optical film 100 is for refracting light incident thereto in adirection and emitting the light in any of various other directionsbased on locations of incidences, where lights are mixed by the opticalfilm 100. Detailed descriptions thereof will be given below withreference to FIGS. 2 and 3.

FIG. 2 is a sectional view taken along a line A-A′ of FIG. 1, showing alight path in which light that is perpendicularly incident to theoptical film is emitted. FIG. 3 is a sectional view taken along a lineA-A′ of FIG. 1, showing a light path in which light that is incident tothe optical film at a tilted angle is emitted.

Referring to FIGS. 2 and 3, the interface between the high refractiveindex pattern layer 110 and the low refractive index pattern layer 120includes a curved surface 110 a constituting the groove GR and a flatsurface 110 b, where the curved surface 110 a functions as a lenssurface.

Referring to FIG. 2, light perpendicularly incident to the optical film100 is refracted to different directions according to locations at whichthe light contacts the curved surface 110 a and is emitted from theoptical film 100. In other words, light beams having a same angle ofincidence are refracted to various directions according to respectivelocations at which the light beams contact the curved surface 110 a, andthus light is diffused.

Furthermore, referring to FIG. 3, light beams incident to the opticalfilm 100 at tilted angles are refracted to various directions accordingto respective locations of incidences of the light beams. In detail, alight beam L1 which is transmitted through the flat surface 110 b andcontacts the curved surface 110 a at the high refractive index patternlayer 110 is totally reflected by the curved surface 110 a and isemitted out of the optical film 100. In the light path, an angle atwhich the light beam L1 is emitted from the top surface of the highrefractive index pattern layer 110 is smaller than the angle at whichthe light beam L1 is incident to the optical film 100. Meanwhile, alight beam L2 which is transmitted through the flat surface 110 bwithout being transmitted through the curved surface 110 a is refracted,such that a refraction angle at the interface between the highrefractive index pattern layer 110 and outside is greater than the angleof incidence, and thus the light beam L2 is emitted from the opticalfilm 100 at an angle greater than the angle of incidence. Furthermore, alight beam L3 which contacts the curved surface 110 a at the lowrefractive index pattern layer 120 is refracted at the curved surface110 a and is refracted again at the top surface of the high refractiveindex pattern layer 110, and thus the light beam L3 is emitted from theoptical film 100 at a greater angle as compared to the light beam L2which is transmitted through the flat surface 110 b and is emitted fromthe optical film 100 without contacting the curved surface 110 a. Asdescribed above, the light beams L1, L2, and L3 that are incident to theoptical film 100 at a same tilted angle are emitted from the opticalfilm 100 at different refraction angles according to the respectivelocations of incidence.

As described above, light that is transmitted through the optical film100 is a mixture of light beams that are incident to the optical film100 at various angles.

In the description given above, the detailed light path at whichincident light is diffused is merely an example. Light paths may varyaccording to a difference between refractive indexes of the highrefractive index pattern layer 110 and the low refractive index patternlayer 120, an aspect ratio of the groove GR at the high refractive indexpattern layer 110, a shape of the curved surface of the groove GR, andan occupation ratio of the groove GR, and a mixture of light orbrightness of emitted light may vary based on the light paths.

Due to the light mixing feature, when light beams are incident to theoptical film 100 having different optical properties according to anglesof incidence, the optical features may be equally mixed for an emittedlight. For example, when light beams are emitted out of an OLED, colorshifts may occur. In other words, the color properties may slightly varyaccording to the angles of emission. However, after such the light beamsare transmitted through the optical film 100 having a structure asdescribed above, the color shifts are mixed, and thus color shiftsaccording to viewing angles may be reduced.

FIG. 4 is a computer simulation graph showing color shift (Δu′v′)according to a variation of tilt angle θ in the optical film of FIG. 1.

The computer simulation is performed by using an illumination opticalsimulation program, and from the result of the simulation on an organiclight-emitting device panel including a microcavity structure, the colorshifts (Δu′v′) at a set (or, predetermined) viewing angle are calculatedbased on front white(x, y)=(0.28, 0.29).

Detailed data shown in the graph is shown below in Table 1.

TABLE 1 case# θ (°) Width (A)(um) Depth (d)(um) Cycle (C)(um) Δu′v′ 13.95 10 2 34 0.0384 2 9.78 10 5 34 0.031 3 17.24 10 9 34 0.02 4 46.22 1024 28 0.0125 5 55.3 10 26 23 0.0098 6 63.43 10 36 23 0.0156 7 69.4 10 129.5 0.019 8 74.5 10 36 15 0.023

Referring to the graph shown in FIG. 4, as the tilt angle θ increases,the color shift (Δu′v′) decreases and increases again. In other words,the color shift (Δu′v′) decreases until a particular tilt angle θ, whichis about 60°, and the color shift (Δu′v′) increases again when the tiltangle θ exceeds the particular tilt angle θ.

It seems that the reason for the increase in the color shift (Δu′v′) isdiffusion, which becomes subtle as the tilt angle θ exceeds a set (or,predetermined) value. In other words, as described above with referenceto FIG. 3, while it is necessary for light beams (e.g., a light beam L1,a light beam L2, and a light beam L3) to be suitably mixed to decreasethe color shift, a percentage of a light beam (like the light beam L3)decreases.

Overall, the color shift graph exhibits a V-like shape around aparticular angle. Generally, it is known that, when a lateral side colorshift is less than about 0.02, human eyes can barely recognize the colorshift. Therefore, a range between 15°<θ<75°, or 15°≦θ≦75°, for example,may be effective for improving color shift. Furthermore, the greater theθ is, the more difficult manufacturing process may become. Therefore, arange between 15°<θ<65°, or 15°≦θ≦65°, may be employed in considerationof difficulties in manufacturing process.

FIG. 5 is a computer simulation graph showing transmittance and colorshift (Δu′v′) according to change of pattern density in the optical filmof FIG. 1.

Detailed data shown in the graph is shown below in Table 2.

TABLE 2 Width Cycle (A) Depth (C) Transmittance case# A/C θ (°) (um) (d)(um) (um) Δu′v′ (%) 1 0.18 55.4 9 66 50 0.0227 97.5% 2 0.2 55.7 10 66 500.0213   97% 3 0.22 55.6 11 65 50 0.02 96.4% 4 0.435 55.3 10 26 230.0098 87.6% 5 0.5 55.7 10 22 20 0.087 84.3% 6 0.55 55.4 11 21 20 0.09381.3%

In the graph shown in FIG. 5, the tilt angle θ is fixed to an anglearound 55°, and color shifts and transmittances according to A/C areshown.

When color shift improvement and front transmittance are calculated foreach case, the color shift decreases as A/C increases, and increasesagain when A/C is about 0.5 as shown in the graph. Furthermore, thefront transmittance decreases in linear fashion as A/C increases.Because the optical film 100 is a film to be arranged in front of adisplay panel, transmittance below or equal to a particular level ismeaningless. Therefore, A/C may be less than or equal to 0.5, at which acolor shift improvement is slowed down or reversed, to be more effectivefor improving color shift.

Hereinafter, structures of optical films according to various exampleembodiments will be described.

FIG. 6 is a schematic perspective view of an optical film according toother example embodiments.

The optical film 101 has a structure in which a plurality of grooves GRincluding curved surfaces are engraved, where the depth of the groove GRis greater than the width of the groove GR. The optical film 101includes the high refractive index pattern layer 110 that is formed of amaterial having a refractive index greater than 1, and a low refractiveindex pattern layer 121 that is formed of a material having a refractiveindex smaller than that of the material constituting the high refractiveindex pattern layer 110.

The grooves GR may be formed using techniques known in the art. Forexample, a high refractive index layer (not shown) may be etched usingphotolithography techniques, wet or dry chemical mechanical polishing orsimilar techniques.

Compared to the previous example embodiments, the optical film 101according to the present example embodiments includes the low refractiveindex pattern layer 121. In other words, compared to the optical film100 of FIG. 1, instead of arranging the film-type low refractive indexpattern layer 120 including protrusions, the grooves GR are filled witha low refractive index material. The low refractive index material maybe a resin material or the air or another gas medium.

FIG. 7 is a schematic exploded perspective view of an optical filmaccording to still other example embodiments.

Referring to FIG. 7, an optical film 200 includes a high refractiveindex pattern layer 210 including a plurality of engraved grooves GRincluding curved surfaces, and a low refractive index pattern layer 220which is formed on the high refractive index pattern layer 210. The lowrefractive index pattern layer 220 is formed of a material having arefractive index smaller than that of the material constituting the highrefractive index pattern layer 110, and includes protrusions Pconstituting a pattern corresponding to the plurality of grooves GR.

The optical film 200 according to the present example embodiments isidentical to the optical film 100 of FIG. except that the grooves GRconstitute a dotted pattern from the perspective view with respect tothe high refractive index pattern layer 210.

FIG. 8 is a schematic exploded perspective view of an optical filmaccording to further example embodiments.

Referring to FIG. 8, an optical film 201 according to the presentexample embodiments is identical to the optical film 200 of FIG. 5except the structure of a low refractive index pattern layer 221. Inother words, instead of arranging the film-type low refractive indexpattern layer 220 including the protrusions P, the grooves GRconstituting a dotted pattern are filled with a low refractive indexmaterial, where the low refractive index material may be a resinmaterial or the air.

The optical films 100, 101, 200, and 201 described above may furtherinclude anti-reflection layers, circular polarization layers, ortransmittance adjusting layers, as well as adhesive layer which may beneeded when the optical films are to be applied to an organiclight-emitting display apparatus.

Hereinafter, structures of optical films according to exampleembodiments will be described in detail.

FIG. 9 is a schematic sectional view of an optical film according tostill further example embodiments.

Referring to FIG. 9, an optical film 300 includes the high refractiveindex pattern layer 110 and the low refractive index pattern layer 120.The high refractive index pattern layer 110 includes a plurality ofgrooves GR, whereas the low refractive index pattern layer 120 is formedof a material having a lower refractive index than a materialconstituting the high refractive index pattern layer 110, and includes afilling material which fills the plurality of grooves GR formed in thehigh refractive index pattern layer 110. Other than the structure shownin FIG. 7, the structures including the high refractive index patternlayer 210 and the low refractive index pattern layers 121, 220, and 221may be applied.

Furthermore, a first base 320 may be further formed on the highrefractive index pattern layer 110. The first base 320 may be formed ofan optically isotropic material, e.g., triacetyl cellulose (TAC).

A circular polarization layer 340 may be further arranged on the firstbase 320, where the circular polarization layer 340 may include a phaseshift layer 342, a linear polarization layer 344, and a second base 346.The second base 346 an optically isotropic material, e.g., triacetylcellulose (TAC). However, example embodiments are not limited thereto.For example, if a film to be arranged on the first base 320 is not acircular polarization layer, the second base 346 may be formed of PET orPC.

Furthermore, a first adhesive film 330 may be further formed between thefirst base 320 and the circular polarization layer 340. The firstadhesive film 330 may be formed of a pressure sensitive adhesion (PSA)material or a PSA material containing a light absorber or a lightdiffuser.

Furthermore, a second adhesive film 310 may be further formed on thebottom surface of the low refractive index pattern layer 120. The bottomsurface of the low refractive index pattern layer 120 opposes thesurface of the low refractive index pattern layer 120 contacting thehigh refractive index pattern layer 110. The bottom surface of the lowrefractive index pattern layer 120 becomes the surface that is adheredto an organic light-emitting display panel when the optical film 300 isapplied to an organic light-emitting display apparatus. The secondadhesive film 310 may be formed of a PSA material containing a lightabsorber or a light diffuser.

FIG. 10 is a schematic sectional view of an optical film according toyet other example embodiments.

Referring to FIG. 10, an optical film 905 has a structure in which ananti-reflection layer 190 is formed on the high refractive pattern layer110 and a first adhesive layer 131 is formed below the low refractivepattern layer 120, where a first base 141 may be further formed betweenthe high refractive pattern layer 110 and the anti-reflection layer 190.

The anti-reflection layer 190 may have a multi-layer structure in whichinorganic materials having different refractive indexes are stacked. Forexample, the anti-reflection layer 190 may have a double-layer structureincluding a high refractive layer and a low refractive layer.

The first adhesive layer 131 is a layer for adhesion to an organiclight-emitting panel, and may be formed of a PSA material or a PSAmaterial containing a light absorber or a light diffuser. Furthermore,the high refractive pattern layer 110 and/or the low refractive patternlayer 120 may be formed of a transparent material containing a lightabsorber. When materials including light absorbers are applied tovarious layers constituting an optical film, reflection of ambient lightmay be reduced, thereby improving visibility.

The first base 141 is used as a base for forming the high refractivepattern layer 110 and the low refractive pattern layer 120, and may beformed of an optical isotropic material, e.g., TAC.

FIGS. 11 through 17 are schematic sectional views of optical filmsaccording to example embodiments employing circular polarization layersand anti-reflection layers.

A circular polarization layer may include a phase shift layer 150 and alinear polarization layer 160.

The phase shift layer 150 may be a λ/4 phase difference film.

The linear polarization layer 160 may include a polyvinyl alcohol (PVA)film and may have a stacked structure including a TAC film or any ofvarious other structures. A PVA film is a film for light polarizationand may be formed by adsorbing a dichroic dye to a polyvinylalcohol,which is a polymer material.

Referring to FIGS. 11 and 12, optical films 906 and 907 includes theadhesive layer 131, the low refractive pattern layer 120, the highrefractive pattern layer 110, the phase shift layer 150, the linearpolarization layer 160, the first base 141, and the anti-reflectionlayer 190 that are stacked from below in the order stated.

The circular polarization layer, which includes the phase shift layer150 and the linear polarization layer 160, increases visibility byreducing reflection of ambient light. When an unpolarized ambient lightis incident, ambient light passes through the linear polarization layer160 and is linearly polarized, and then the linearly polarized light iscircularly polarized by the phase shift layer 150. Next, the circularlypolarized light passes through the interface between the phase shiftlayer 150 and the high refractive pattern layer 110, the high refractivepattern layer 110, the low refractive pattern layer 120, and the firstadhesive layer 131, and is reflected at the interface between the firstadhesive layer 131 and an organic light-emitting panel (not shown), andbecomes a circularly polarized light with an opposite direction ofrevolution. Next, this circularly polarized light passes through thephase shift layer 150, becomes a linearly polarized light that isperpendicular to the transmittance axis of the linear polarization layer160, and is not emitted to outside.

As shown in FIGS. 11 and 12, the circular polarization layer is arrangedon the high refractive pattern layer 110. Therefore, if the highrefractive pattern layer 110 is formed of an anisotropic material havinga different optical axis from the circular polarization layer,polarization does not occur, and thus incident outer light may beemitted to outside again. As a result, reflection may significantlyincrease, and thus visibility may be deteriorated. Therefore, it isnecessary to form the high refractive pattern layer 110 using anisotropic material having the same optical axis as the circularpolarization layer, e.g., TAC or solvent-casted polycarbonate (PC).

Compared to the optical film 906 of FIG. 11, the optical film 907 ofFIG. 12 further includes a second base 142 and a second adhesive layer132 between the high refractive pattern layer 110 and the phase shiftlayer 150, where the second base 142 and the second adhesive layer 132are formed in the order stated from the high refractive pattern layer110 to the phase shift layer 150.

Referring to FIGS. 13 and 14, optical films 908 and 909 include thefirst adhesive layer 131, the phase shift layer 150, the linearpolarization layer 160, the low refractive pattern layer 120, the highrefractive pattern layer 110, the first base 141, and theanti-reflection layer 190.

The optical film 909 of FIG. 14 further includes the second base 142 andthe second adhesive layer 132 between the linear polarization layer 160and the low refractive pattern layer 120, where the second base 142 andthe second adhesive layer 132 are formed in the order stated from thelinear polarization layer 160 to the low refractive pattern layer 120.

Referring to FIGS. 15 and 16, optical films 910 and 911 include thefirst adhesive layer 131, the phase shift layer 150, the low refractivepattern layer 120, the high refractive pattern layer 110, the linearpolarization layer 160, the first base 141, and the anti-reflectionlayer 190 that are arranged from below in the order stated.

The optical film 911 of FIG. 16 further includes the second base 142between the high refractive pattern layer 110 and the linearpolarization layer 160.

Referring to FIG. 17, optical film 912 includes the first adhesive layer131, the phase shift layer 150, the linear polarization layer 160, thefirst base 141, the low refractive pattern layer 120, the highrefractive pattern layer 110, and the anti-reflection layer 190 that arearranged in the order stated.

FIGS. 18 through 20 are schematic sectional views of optical filmsaccording to example embodiments employing transmittance adjustinglayers and anti-reflection layers.

A transmittance adjusting layer 170 may be a film formed by diffusing ablack material for absorbing light, e.g., a black dye, a black pigment,carbon black, or particles coated therewith to a polymer resin. Thepolymer resin may not only be a binder like PMMA, but also a UV curableresin, such as an acrylic resin. However, example embodiments are notlimited thereto. Furthermore, a thickness of the transmittance adjustinglayer 170, or a concentration of the black material in the polymerresin, may be suitably determined based on the optical properties of theblack material. Transmittance of the transmittance adjusting layer 170may be 40% or higher, which is slightly higher than transmittance of acircular polarization layer. Although a circular polarization layer iscapable of almost completely blocking outer light, the circularpolarization layer exhibits low transmittance. Therefore, thetransmittance adjusting layer 170 is employed.

Referring to FIGS. 18 and 19, optical films 913 and 914 include thefirst adhesive layer 131, the low refractive pattern layer 120, the highrefractive pattern layer 110, a first carrier film 181, thetransmittance adjusting layer 170, and the anti-reflection layer 190that are arranged in the order stated from below.

The optical film 914 of FIG. 19 further includes the second adhesivelayer 132 between the first carrier film 181 and the transmittanceadjusting layer 170, and a second carrier film 182 between thetransmittance adjusting layer 170 and the anti-reflection layer 190.

Referring to FIGS. 20 and 21, optical films 915 and 916 include thefirst adhesive layer 131, the low refractive pattern layer 120, the highrefractive pattern layer 110, the transmittance adjusting layer 170, thefirst carrier film 181, and the anti-reflection layer 190 that arearranged in the order stated from below.

The optical film 916 of FIG. 21 further includes the second adhesivelayer 132 between the high refractive pattern layer 110 and thetransmittance adjusting layer 170, and the second carrier film 182between the first adhesive layer 131 and the low refractive patternlayer 120.

The first carrier film 181 and the second carrier film 182 are used asbases for forming the high refractive pattern layer 110 and the lowrefractive pattern layer 120, or bases for forming the anti-reflectionlayer 190 and the transmittance adjusting layer 170. Because the opticalfilms of FIGS. 16 through 19 do not include linear polarization layers,the polarization retaining function is not necessary. Therefore, any ofvarious materials including TAC, PET, and PC may be used as the bases.

Although the high refractive pattern layer 110 and the low refractivepattern layer 120 of the optical films 915 and 916 of FIGS. 11 through21 may have a shape of those shown in FIG. 1, example embodiments arenot limited thereto, and the high refractive pattern layer 110 and thelow refractive pattern layer 120 may have a shape of those shown inFIGS. 6 through 8.

FIG. 22 is a sectional view of an organic light-emitting displayapparatus according to some example embodiments, and FIG. 23schematically shows a relationship between arrangement of an adhesivelayer and pixel arrangement of an organic light-emitting display panelin the organic light-emitting display apparatus of FIG. 22.

Referring to FIG. 22, an organic light-emitting display apparatus 500includes an organic light-emitting display panel 510 including aplurality of pixels which emit light of different wavelengths, andincluding organic light-emitting layers having a microcavity structureresonating light of the corresponding wavelengths, and an optical film530 arranged on the organic light-emitting display panel 510. Anadhesive layer 520 may be further formed between the organiclight-emitting display panel 510 and the optical film 530. Furthermore,a circular polarization layer 540 may be further arranged on the opticalfilm 530.

The organic light-emitting display panel 510 is formed to have amicrocavity structure to improve brightness and color purity. In otherwords, the organic light-emitting display panel 510 includes a pluralityof OLEDs each of which emits red light, green light, or blue light,where each of the OLEDs includes anodes 13, an organic light-emittinglayer 14, and cathodes 15. As shown in FIG. 7, in the case of theorganic light-emitting display panel 510 including OLEDs that arearranged such that an unit pixel embodies red color (R), green color(G), and blue color (B), the organic light-emitting display panel 510 isformed to have a microcavity structure in which the distance between theanode 13 and the cathode 15 of a red OLED corresponding to longerwavelength is the greatest, and the distance between the anode 13 andthe cathode 15 of a blue OLED corresponding to shorter wavelength is theshortest. In other words, the organic light-emitting display panel 510is formed such that distances between the anodes 13 and the cathodes 15are respectively matched to the representative wavelengths of red color,green color, and blue color. Therefore, only light of correspondingwavelengths are resonated and emitted outside of the organiclight-emitting display panel, and light of other wavelengths areweakened.

Detailed descriptions of the organic light-emitting display panel willbe given below.

Each sub-pixel of the organic light-emitting display panel 510 may beformed of an OLED which is arranged between a first substrate 11 and asecond substrate 19 facing each other, and includes the anode 13, theorganic light-emitting layer 14, and the cathode 15, and a drivingcircuit 12, which is formed on the first substrate 11 and iselectrically connected to the anode 13, and the cathode 15.

Here, the anode 13 may be formed of an opaque metal, such as aluminum(Al), whereas the cathode 15 may be formed of a transparent electrode,such as indium tin oxide (ITO), or formed as a semi-transparentelectrode formed of nickel (Ni) thin-film to transmit light emitted bythe organic light-emitting layer 14.

The driving circuit 12 may include at least two thin-film transistor(TFTs) (not shown) and capacitors (not shown) and controls luminance ofan OLED by controlling current supplied to the OLED according to datasignals.

The driving circuit 12 is a circuit for driving a unit pixel of theorganic light-emitting display panel 510, and may include a gate line, adata line perpendicularly crossing the gate line, a switching TFTconnected to the gate line and the data line, a driving TFT which isconnected to an OLED between the switching TFT and a power line, and astorage capacitor interconnecting a gate electrode of the driving TFTand the power line.

Here, the switching TFT supplies a data signal of the data line to thegate electrode of the driving TFT and the storage capacitor in responseto a scan signal from the gate line. In response to the data signal fromthe switching TFT, the driving TFT controls luminance of an OLED bycontrolling current supplied from a power line to the OLED. Furthermore,the storage capacitor charges data signals from the switching TFT andsupplies charged voltage to the driving TFT, such that the driving TFTis capable of supplying constant current even if the switching TFT isturned off.

The organic light-emitting layer 14 includes a hole injection layer, ahole transport layer, a light-emitting layer, an electron transportlayer, and an electron injection layer. Therefore, when a forwardvoltage is applied between the anode 13 and the cathode 15, electronsmove from the cathode 15 to the light-emitting layer via the electroninjection layer and the electron transport layer, whereas holes movefrom the anode 13 to the light-emitting layer via the hole injectionlayer and the hole transport layer. Next, the electrons and the holesinjected into the light-emitting layer are re-combined at thelight-emitting layer and generate excitons. Light is emitted from thelight-emitting layer as the excitons transit from the excited state tothe ground state, where brightness of the emitted light is proportionalto a current flowing between the anode 13 and the cathode 15.

Furthermore, the organic light-emitting display panel 510 includes acolor filter 17 to improve color efficiency. Here, the color filter 17is formed on the second substrate 19, where a red color filter is formedin a red sub-pixel region, a green color filter is formed in a greensub-pixel region, and a blue color filter is formed in a blue sub-pixelregion. If a unit pixel is embodied to emit light of four colors (red,green, blue, and white), the color filter 17 may be omitted at a whitesub-pixel region.

Furthermore, although not shown, a black matrix for preventing lightleakage and color mixture may be formed on the second substrate 19 atboundaries between sub-pixels. Furthermore, spacers may be formed for anelectrical connection between the anode 13 and the cathode 15, and anelectrical connection between the anode 13 and the driving circuit 12,where the electrical connections may be formed by attaching the firstsubstrate 11 and the second substrate 19 toward each other via a sealingmember.

Meanwhile, in the organic light-emitting display apparatus 500 havingthe microcavity structure, the maximum resonating wavelength decreasesas viewing angle is tilted, and thus a color shift occurs toward shorterwavelength. For example, even if white color is embodied at the front,the white color may become bluish at a lateral side due to a blue shiftphenomenon.

The organic light-emitting display apparatus 500 according to thepresent example embodiments includes the optical film 530 arranged onthe organic light-emitting display panel 510 to reduce the color shift.The optical film 530 includes a high refractive index pattern layer 531which includes a plurality of engraved grooves GR having curved surfacesand is formed of a material having a refractive index greater than 1,and a low refractive index pattern layer 532 which is formed on the highrefractive index pattern layer 531, is formed of a material having alower refractive index than the material constituting the highrefractive index pattern layer 531, and includes a filling material forfilling the plurality of grooves GR.

The optical film 530 may have a shape of any of the various opticalfilms 100, 101, 200, and 201 that are described above with reference toFIGS. 1 through 6.

The grooves GR of the optical film 530 may extend like stripes. In thiscase, the optical film 530 may be arranged on the organic light-emittingdisplay panel 510, such that the stripes extend across the organiclight-emitting display panel 510 in a vertical direction. Furthermore,the optical film 530 may be arranged on the organic light-emittingdisplay panel 510, such that an integer number of the grooves GR fromamong the grooves GR of the optical film 530 correspond to each pixel ofthe organic light-emitting display panel 510.

As described above with reference to FIGS. 2 and 3, the optical film 530emits light beams, which are incident thereto at a same angle, atvarious angles. Meanwhile, light beams emitted by the organiclight-emitting display panel 510 have a set (or, predetermined) angledistribution, where color shifting properties slightly vary from oneanother according to the angles. When such a light beam is transmittedthrough the optical film 530, light beams incident to the optical film530 at angles corresponding to relatively great color shift are mixedwith light beams incident to the optical film 530 at anglescorresponding to relatively small color shift, and thus color shiftsbased on viewing angles are reduced.

Meanwhile, as shown in FIG. 23, a plurality of pixels R, G, and B of theorganic light-emitting display panel 510 may be two-dimensionallyarranged at an organic light-emitting display panel in four directionsacross the organic light-emitting display panel, where the direction inwhich the stripes formed by the grooves GR extend and the verticaldirection in which the plurality of pixels are arranged may not beparallel to each other. If the grooves GR constitute a stripe pattern, aMoiré pattern may occurs due to mutual interference between the organiclight-emitting display panel 510 and the optical film 530. However, asshown in FIG. 9, if a set (or, predetermined) angle is formed betweenthe direction in which the stripes formed by the grooves GR extend andthe vertical direction in which the plurality of pixels are arranged,the occurrence of the Moiré pattern may be reduced (or, prevented).

The adhesive layer 520 may be formed between the organic light-emittingdisplay panel 510 and the optical film 530. The adhesive layer 520 maybe formed of a PSA material containing a light absorber and a lightdiffuser, for example.

Furthermore, the low refractive index pattern layer 531 and/or the lowrefractive index pattern layer 532 may be formed of a transparentmaterial containing a light absorber.

As described above, if a material containing a light absorber is appliedto the adhesive layer 520 or the optical film 530, reflectivity ofexternal light may be reduced, thereby improving visibility.

Furthermore, the circular polarization layer 540 may be further arrangedon the optical film 530, where the circular polarization layer 540 mayinclude a linear polarization layer 544 and a phase shift layer 542.

The linear polarization layer 544 may include a TAC film and a polyvinylalcohol (PVA) film. For example, the linear polarization layer 544 mayhave a TAC film/PVA film/TAC film stacked structure. Structure of thelinear polarization layer 544 may further vary. Here, the PVA film is afilm for light polarization and may be formed by absorbing a dichroicdye to a PVA, which is a polymer material. Furthermore, the TAC filmsarranged on the two opposite surfaces of the PVA film support the PVAfilm.

The phase shift layer 542 may be a λ/4 phase difference film.

The circular polarization layer 540 improves visibility by reducingreflectivity of external light. When external light that is notpolarized is incident, the external light is linearly polarized as theexternal light is transmitted through the linear polarization layer 544and is circularly polarized by the phase shift layer 542. Next, thecircularly polarized light is reflected at the interface between thephase shift layer 542 and the optical film 530, or the interface betweenthe optical film 530 and the organic light-emitting display panel 510and is circularly polarized in the opposite revolving direction. Next,the circularly polarized light is linearly polarized in a directionperpendicular to the transmitting axis of the linear polarization layer544 as the circularly polarized light is transmitted through the phaseshift layer 542. As a result, the polarized light is not emitted tooutside.

As shown in FIG. 22, the circular polarization layer 540 is arranged onthe optical film 530. Therefore, if the high refractive index patternlayer 531 constituting the optical film 530 is formed of an anisotropicmaterial having an optical axis different from that of the circularpolarization layer 540, polarization may be broken and incident externallight may be re-emitted to outside. As a result, reflection of theorganic light-emitting display panel 510 may significantly increase,thereby deteriorating visibility of the organic light-emitting displaypanel 510. Therefore, it is necessary to form the high refractive indexpattern layer 531 of a material having the same optical axis as thecircular polarization layer 540, e.g., TAC or solvent-castedpolycarbonate (PC).

Although FIG. 22 shows that the phase shift layer 542 and the linearpolarization layer 544 are formed on the optical film 530 in the orderstated. However, the structure is merely an example. For example, theoptical film 530 may be arranged between the phase shift layer 542 andthe linear polarization layer 544.

Although the optical film 530 is arranged to reduce color shiftsaccording to viewing angles, image distortion may be induced thereby.Therefore, to reduce image distortion as much as possible, a distancebetween the organic light-emitting layer 14 and the optical film 530 maybe less than or equal to about 1.5 mm.

FIG. 24 is a graph showing a comparison between color shifts accordingto viewing angles in a case where an optical film according to exampleembodiments is employed and color shifts according to viewing angles ina conventional optical film.

The horizontal axis of the graph indicates viewing angles, whereas thevertical axis of the graph indicates degrees of deviations fromreference color coordinates.

Referring to FIG. 24, color shifts according to viewing angles isrelatively small in the case where an optical film according to exampleembodiments is employed. Furthermore, when a light diffuser is alsoused, apexes corresponding to particular grooves are removed from thegraph indicating color shifts according to viewing angles, and thus thegraph has a smooth shape.

FIG. 25 is a graph showing a comparison between brightnesses accordingto viewing angles in a case where an optical film according to exampleembodiments is employed and brightnesses according to viewing angles ina conventional optical film.

Referring to FIG. 25, brightness distribution corresponding to the casein which the optical film according to example embodiments is employedis similar to brightness distribution corresponding to the conventionaloptical film. Furthermore, when a light diffuser is also used, apexescorresponding to particular grooves are removed from the graphindicating brightnesses according to viewing angles, and thus the graphhas a smooth shape.

In the graphs shown in FIGS. 24 and 25, the optical film applied to theorganic light-emitting display apparatus according to exampleembodiments barely affects brightness distribution according to viewingangles and reduces color shifts according to viewing angles.

FIG. 26 is a schematic sectional view showing an organic light-emittingdisplay apparatus according to other example embodiments.

Referring to FIG. 26, an organic light-emitting display apparatus 600includes the organic light-emitting display panel 510 and the opticalfilm 300. The optical film 300 may have the structure shown in FIG. 7.In other words, the optical film 300 may include the adhesive film 310,the low refractive index pattern layer 120, the high refractive indexpattern layer 110, the first base 320, the adhesive film 330, and thecircular polarization layer 340, where the circular polarization layer340 may include the phase shift layer 342, the linear polarization layer344, and the second base 346.

The first base 320 and the second base 346 may be formed of opticallyisotropic materials, e.g., TAC. The adhesive film 310 and the adhesivefilm 330 may be formed of PSA material or PSA material containing alight absorber and a light diffuser.

The low refractive index pattern layer 120 and the high refractive indexpattern layer 110 may also have the structures as shown in FIGS. 6through 8.

Although the optical film 300 employed by the organic light-emittingdisplay apparatus 600 has the structure shown in FIG. 9, it is merely anexample, and the organic light-emitting display apparatus 600 may employthe optical films 915 through 912 of FIGS. 10 through 21.

The optical film as described above refracts and emits light beams,which are incident thereto at the vertical angle and tilted angles, atvarious angles.

Therefore, an organic light-emitting display apparatus employing theoptical film as described above may include an organic light-emittinglayer having a microcavity structure capable of improving color purity.Furthermore, color shifts according to viewing angles may be reduced,and thus high quality images may be provided.

It should be understood that the example embodiments described thereinshould be considered in a descriptive sense only and not for purposes oflimitation. Descriptions of features within each example embodimentshould typically be considered as available for other similar featuresin other example embodiments.

What is claimed is:
 1. An optical film, comprising: a high refractiveindex pattern layer including a first surface and a second surfacefacing each other, wherein the first surface includes a pattern having aplurality of grooves, the plurality of grooves each have a curvedsurface and a depth greater than a width thereof, and the highrefractive index pattern layer is formed of a material having arefractive index greater than 1; and a low refractive index patternlayer formed of a material having a refractive index smaller than therefractive index of the material constituting the high refractive indexpattern layer, wherein the low refractive index pattern layer includes afilling material for filling the plurality of grooves, wherein a tiltangle, θ, of each groove satisfies the following condition, 15°≦θ≦75°,the tilt angle is an angle between a straight line and the firstsurface, the straight line connects an apex of the respective groove toa start point of an adjacent groove on the first surface, and lightincident through the low refractive index pattern layer is emittedthrough the second surface of the high refractive pattern layer.
 2. Theoptical film of claim 1, wherein the plurality of grooves arecollectively repeated in a cycle, C, and the condition, A/C<0.5, issatisfied where A is the width of the groove.
 3. The optical film ofclaim 1, wherein the filling material includes air or a resin material.4. The optical film of claim 1, wherein the low refractive index patternlayer is shaped in the form of a film having a plurality of protrusionpatterns, and the plurality of protrusion patterns corresponds to theplurality of grooves.
 5. The optical film of claim 4, wherein the lowrefractive index pattern layer includes a transparent plastic materialincluding a light diffuser or a light absorber.
 6. The optical film ofclaim 1, wherein the plurality of grooves each have an extended stripeshape.
 7. The optical film of claim 1, wherein the plurality of grooveseach have a dot shape from a perspective view with respect to the highrefractive index pattern layer.
 8. The optical film of claim 1, whereinthe curved surface of the plurality of grooves is an aspherical surface.9. The optical film of claim 1, further comprising: an anti-reflectionlayer on the high refractive index pattern layer; and a first adhesivelayer under the low refractive index pattern layer.
 10. The optical filmof claim 9, wherein a first base layer is between the high refractiveindex pattern layer and the anti-reflection layer.
 11. The optical filmof claim 10, further comprising: a circular polarization layer betweenthe high refractive index pattern layer and the anti-reflection layer,the circular polarization layer including a phase shift layer and alinear polarization layer.
 12. The optical film of claim 11, wherein thefirst adhesive layer, the low refractive index pattern layer, the highrefractive index pattern layer, the phase shift layer, the linearpolarization layer, the first base layer, and the anti-reflection layerare sequentially arranged.
 13. The optical film of claim 9, furthercomprising: a phase shift layer, a linear polarization layer, and afirst base layer, wherein the first adhesive layer, the phase shiftlayer, the linear polarization layer, the first base layer, and the lowrefractive index pattern layer are sequentially arranged.
 14. Theoptical film of claim 9, further comprising: a transmittance adjustinglayer between the high refractive index pattern layer and theanti-reflection layer.
 15. An organic light-emitting display apparatus,comprising: an organic light-emitting display panel including aplurality of pixels emitting light of different wavelengths, and aplurality of organic light-emitting layers each having a microcavitystructure configured to resonate and emit light of a correspondingwavelength; and the optical film according to claim 1 on the organiclight-emitting display panel.
 16. The organic light-emitting displayapparatus of claim 15, wherein the plurality of grooves each have anextended stripe shape.
 17. The organic light-emitting display apparatusof claim 16, wherein an extending direction of the plurality of groovescorresponds to a vertical direction of the organic light-emittingdisplay panel.
 18. The organic light-emitting display apparatus of claim17, wherein the plurality of pixels are two-dimensionally arranged alonga vertical direction and a horizontal direction of the organiclight-emitting display panel, and the extending direction of the groovesand the vertical direction in which the plurality of pixels are arrangedare non-parallel to each other.
 19. The organic light-emitting displaydevice of claim 15, further comprising: a first adhesive layer betweenthe organic light-emitting display panel and the low refractive indexpattern layer; and an anti-reflection layer on the high refractive indexpattern layer.
 20. The organic light-emitting display device of claim19, further comprising: a circular polarization layer including a phaseshift layer and a linear polarization layer.